The Soviet Rationale of Foregoing Disinformation in The Case of The Berlin Tunnel
West Point Press
"The tensions of the Cold War were largely the product of uncertainty. In Europe, the Americans and the British could no longer collect radio communications as they had in the past, for the Soviets had switched from “longwave,” easy to intercept frequencies, to “shortwave” frequencies that operated only within line-of-sight.1 Along the Iron Curtain there was little opportunity to listen in on radio transmissions over the airwaves, but there was ground wire in place that the Americans and British recognized and chose to exploit with the Berlin Tunnel...."
Pachesny, Tyler. “The Soviet Rationale of Foregoing Disinformation in The Case of The Berlin Tunnel.” Report: West Point Undergraduate Historical Review. Volume 9 (2019): 5-11.